CORS error

tvhnet2013

Hi,

In server A, we have LightStreamer Moderator 5.1.2.
In server B, we host our web application using LightStreamer Client Version 6.1.1 build 1640.2.

Recently, our web app gets hang after running one or two days continuously on Chrome 45. We try to run it on latest Mozilla FireFox and get this error: "Cross-Origin Request Blocked: The Same Origin Policy disallows reading the remote resource at http://myapp.serverA.com/lightstreamer/msg.js. (Reason: CORS request failed)."

Our app has run ok in nearly 2 years continuously.

Please help me to solve this problem.

Thanks & regards,

P/S: I attach our LS config file.

Dario Crivelli

Your Server configuration is not restrictive with respect to cross-origin requests, hence the message you see comes unexpected.
We may even suspect that some intermediate node provided an error response on behalf of LS Server.
We should see the related full HTTP request and response to ascertain that.
Please also clarify if you now see this issue always.

If I understand correctly, you feel that this issue may be the cause of your app hanging on Chrome, but you have no more information to share on that episode.

tvhnet2013

Thanks Dario,

I see this issue every day. For more details, I open many instances of my app. Each instance is running on a tab of Chrome. I must to close and reopen all tabs after a day because of their hangings.

For CORS errror on Firefox, it always happens now.

I have some suspects:

- Incompatibilities between LS client V6.1 and LS server V5.1.2?

- Some recent improvements of Chrome that may suspend my app? But my app does not work on firefox also.

What information or log should I provide to you in order to figure out this issue?

Dario Crivelli

In order to sort out the CORS issue on Firefox, I confirm that we require a full capture of the HTTP request that causes the error.
Since it seems that you are in control of the client, this means opening the browser console and, in the Network tab, identifying the failed request and extracting all request and response headers; preferably, enable and include the capture of the related bodies as well.

As far as Chrome is concerned, I confirm that LS client 6.1 is compatible with Server 5.1.2;
however, there were a few fixes after 6.1,also targeted to Chrome.
So we suggest you trying with the more recent library 6.1.4, which is still compatible with Server 5.1.2;
you should find it in the same package which includes Server 5.1.2.
If the issue persists, we need some evidence that LS is involved in the application hang, similarly to what you did with Firefox.
If the hang happens after the app has been alive for a whole night, could you check if there is an abnormal increase in the overall memory usage (for instance through Chrome's Task Manager)?

tvhnet2013

There is an error in my app that may be due to this issue. I have fixed it and now wait to see how it runs for a while. I'll let you know what happen.

Thank you very much for your support.